Fuel supply assemblies for combustors of gas turbine engines are known to include a fuel manifold extending around the combustor's outer casing to supply fuel to a plurality of fuel nozzles which extend into the combustor, through the outer casing, in order to injection fuel and/or air into the combustion chamber. The interconnections between the fuel nozzles and the fuel manifold are sealed, such as by O-ring seals for example, in order to prevent fuel leaks. However, the fuel nozzles which extend into the combustor are exposed to much higher temperatures than the external fuel manifold, and as such heat is transferred from inner ends of the fuel nozzles to the outer ends thereof, proximate the interface with the fuel manifold. Accordingly, the fuel seals at the interface between the fuel nozzles and the fuel manifold can be exposed to high temperatures, leading to deterioration of their sealing capability over time.